376 Test for Platinum. 



and two feet above low tide, and fifty-six above the highest 

 ground in the city ; is thence conveyed in the iron pipes 

 described in our last Number, (page 173,) the whole ex- 

 tent of which is now thirty-five thousand two hundred and 

 five feet, "and in no instance has a leak been discovered." 

 The greater part of the pipes now laid are of American 

 manufacture, none ever having been imported except as 

 samples. 



The system obviously admits of indefinite extension. 

 The committeejustlyremark that "the uses and importance 

 of this water, it is impossible sufficiently to value. The 

 additional cleanliness of the city, (which with the suburbs 

 contains between 120,000 and 130,000 people,) the supply 

 of the neighboring districts for culinary purposes, as well 

 as for purposes of refreshment — the great advantage in case 

 of fire — the ornament of fountains in the public squares so 

 wisely provided by our great founder — the benefit to man- 

 ufactures, and the establishment of water power in the city 

 for various purposes, may be named among the advantages 

 of this new work ; but above all we are to place its effect 

 upon the health of a great and growing community, which 

 of itself would justify a much greater expenditure." — Ed. 



13. Test for Platinum. 



In the course of various trials, with hydriodic acid, upoQ 

 metallic solutions, we were recently much impressed with 

 its remarkable effect upon the muriate of platinum. If 

 dropped into a solution of this salt, even when extremely 

 dilute, it produces, almost immediately, (and immediately 

 if the solution be of only moderate strength) a deep wine 

 red, or reddish brown colour; by standing a few minutes, 

 itgrovvs much more intense, and becomes very striking, af- 

 ter the lapse often minutes. It much resembles the effect 

 of the recent muriate of tin, but is a more dehcate test than 

 that, as it produces decided results where that gives but a 

 faint change of colour. By standing a day or two, the so- 

 lution becomes covered on the top, and on the sides of the 

 vessel, with a film of perfectly metallic platinum. From 

 this circumstance, it appears that the test operates by redu- 

 cing the solution to the metallic state. Perhaps this effect 

 was favoured by the manner in which the hydriodic acid 



